Hepatocellular carcinoma (HCC) is an often fatal condition due to late diagnosis, resistance to existing anticancer agents, as well as underlying liver disease that can limit the use of hepatotoxic chemotherapy. Proprotein convertases (PCs) are serine proteases that convert a variety of growth factors, cell surface glycoproteins, receptors and metalloproteinases into their active forms, thus regulating the biological activity of these proteins. PCs have been found to be upregulated in various malignancies. Growth factors implicated in HCC, such as IGF-1, HGF, VEGF and PDGF, have all been shown to be converted into their active forms by PCs. In this study, I explored the hypothesis that expression of proprotein convertases, specifically PCSK9, furin and PC5, is elevated in HCC. This was evaluated through construction of a Tissue Microarray and staining for these proteins. We found that PCSK9 expression was significantly downregulated in HCC tumours associated with poorer survival. PCSK9 is upregulated in the context of liver regeneration and has been involved in cholesterol metabolism, with development of monoclonal antibodies against PCSK9 to treat hypercholesterolemia. Its altered expression in aggressive HCC tumours potentially indicates that HCC is able to modulate its local microenvironment to enable a constant energy supply. There has recently been a move in oncology research to study suppression of suppress tumour growth by modifying energy supply and metabolism (for eg, metformin in prostate and breast cancer). Further confirmation at the mRNA level is required to confirm the altered expression of PCSK9, however this appears to be a promising finding and potential chemotherapeutic target. / Contexte et hypothèses: Le carcinome hépatocellulaire (CHC) est le 5e cancer le plus courant dans le monde entier et la 3ème cause de décès par cancer dans le monde entier, avec une survie médiane à 5 ans de 8,9%. La reconnaissance tardive en raison du manque de biomarqueurs pour détecter la maladie résécable, une résistance aux agents anticancéreux, ainsi qu'une maladie du foie sous-jacente limitant l'utilisation de chimiothérapie hépatotoxique sont des facteurs qui diminuent le taux de survie. Les proprotéines convertases (PCs) sont des sérine-protéases qui convertissent une variété de facteurs de croissance, glycoprotéines de surface cellulaire, les récepteurs, et les métalloprotéinases à leurs formes actives, contrôlant ainsi l'activité biologique de ces protéines. On a démontré l'expression augmentée de PCs dans de diverses tumeurs malignes. On a prouvé que les facteurs de croissance impliqués dans le CHC, tels que l'IGF-1, HGF, VEGF et PDGF, sont convertis à leurs forme actives par les PC. Notre hypothèse est que l'expression de proprotéines convertases est élevée dans le CHC, permettant l'activation de différentes protéines essentielles dans le développement et la progression du CHC. L'objectif de recherche était d'évaluer l'expression des PCs PCSK9, furine et PC5 dans le CHC par rapport aux stroma environnant, zones péri-cirrhotiques, et foie normal afin de déterminer si un gradient d'expression existe. PCSK9 en particulier est connu comme étant plus exprimé chez le foie régénérateur post-hepatectomie. Les diapositives de pathologie de CHC stockés dans le département de pathologie du CUSM ont été examinés par une pathologiste, et les zones appropriées (tumeur de CHC, interface de tumeur et du foie, le foie cirrhotique, et d'autres échantillons d'hépatite et de foie normal) dans les blocs de tissu correspondants ont été creusés et ont été incorporées dans un microarray de tissu (TMA). Des lignes cellulaires de CHC etablies, dont le HepG2 et le Huh7, avec des profils d'expression de PC connus, ont été incorporées sous forme de pastilles de cellules dans la TMA, afin de servir de témoins positifs et négatifs. La TMA a été sectionnée en diapositives, qui ont été colorées avec des anticorps de la PCSK9, furine et PC5. On a découvert que le niveau d'expression de PCSK9 était diminuée dans les CHC avec un pire prognostique. L'expression augmentée de PCSK9 dans les CHC plus aggressifs pourrait indiquer un rôle du PCSK9 dans la tumorigenèse, directement ou indirectement. Il se peut que les CHCs plus aggressifs sont capables de modifier l'environnement local pour apprivoiser l'énergie métabolique, et que le PCSK9 permet que le cholestérol soit utilisé comme source d'énergie. La confirmation de son importance fonctionnelle avec mRNA pourrait potentiellement mener au développement de chimiothérapie ciblée avec des anticorps contre le PCSK9 (stratégie en étude pour l'hypercholestérolémie). Compte tenu des options chimiothérapeutiques actuellement limitées pour le CHC, une telle constatation pourrait améliorer la prise en charge clinique du CHC.

Physical and computer-based simulators are used to help residents and medical students practise various surgical techniques. Within the operating room, auditory cognitive distractions often occur. Currently, limited studies examine the effect of increasing task complexity and multi-tasking on expert and novice performance in the operating room. We studied how training on a surgical simulator leads to the development of automaticity. With the LapSim computer simulator, the effect of a secondary dual task on performance of laparoscopic skills tasks was examined. We increased the level of surgical task difficulty to amplify any effects of distraction on performance and to see whether participants could dual-task. A cohort study of 24 participants (undergraduate medical students and expert staff) completed the technical task of cutting a blood vessel on the LapSim at baseline. Participants were then asked only math questions (cognitive task). In the evaluation phase, participants completed both the technical task on the simulator and the cognitive task of answering math questions. We found that expert surgeons were able to dual task at both easy and medium levels of difficulty. This study adds to the growing literature of how dual-tasking and automaticity are achieved as residents learn surgical tasks. / Les simulateurs physiques et informatiques sont fréquemment utilisés pour aider les résidents et étudiants en médecine à pratiquer les techniques chirurgicales. Dans la salle d'opération, il y a souvent des distractions auditives. Actuellement, il y a peu d'études qui examinent l'effet de la complexité des tâches et la capacité de faire plusieurs choses à la fois sur la performance des chirurgiens experts et des novices dans la salle d'opération. Nous avons étudié comment l'entrainement à l'aide d'un simulateur chirurgical peut aider à développer l'automaticité. Avec le simulateur informatique LapSim, nous avons examiné l'effet d'une tâche supplémentaire sur l'exécution de tâches laparoscopiques. Nous avons augmenté le niveau de difficulté de la tâche chirurgicale pour amplifier tout effet de la distraction sur la performance et pour déterminer si les participants pouvaient réaliser deux choses simultanément. Une étude de cohorte de 24 participants (étudiants en médecine et chirurgiens experts) ont complété la tâche technique de couper un vaisseau sanguin sur la LapSim au début. Ensuite, on a posé des questions mathématiques aux participants (tâche cognitive). Durant la phase d'évaluation, les participants ont complété la tâche technique sur le simulateur et la tâche cognitive en même temps. Cette étude s'ajoute à un nombre croissant d'expertises concernant la capacité qu'ont les chirurgiens résidents d'effectuer plusieurs tâches simultanément et de manière automatique lors de procédures chirurgicales.

Brain death is considered a major stress on the body that is associated with a massive inflammatory response or what is known as the "cytokine storm", which is characterized by the exaggerated release of pro-inflammatory cytokines. This heightened inflammatory response in brain dead organ donors leads to major disturbances in glucose homeostasis resulting in insulin resistance and systemic hyperglycemia. Acute hyperglycemia is intimately related to the inflammatory response and marks an increased risk of morbidity and mortality. Severe inflammation in brain dead donors can also lead to increased graft immunogenicity before transplantation and increased risk of graft dysfunction following transplantation. In addition, to the maintenance of normoglycemia Insulin therapy has expressed anti-inflammatory effects in clinical and experimental studies. The rational of this project was to investigate the anti-inflammatory properties of high dose insulin therapy on brain dead organ donors and if this therapy is successful in maintaining normoglycemia in these donors. The anti-inflammatory effect was measured by comparing the change in the levels of serum cytokines in these donors. Insulin therapy was delivered using the hyperinsulinemic normoglycemic clamp (HNC) technique. The study was carried out in the context of a prospective pilot trial registered at clinicaltrial.gov (NCT01304290). Fifteen brain dead organ donors were recruited including 6 donors were given the HNC protocol "experimental group" and 9 donors received routine management "control group". The insulin therapy was provided for a minimum of 6 hours and continued until the organ retrieval procedure. The donors were assigned to either experimental or control groups based on the location of the donation procedure. Blood samples were taken from all patients at various time points. The samples were analyzed to identify the levels of several predetermined inflammatory cytokines. Comparison of the changes in these levels with therapy in both groups was performed. High dose insulin therapy in the form of HNC was successful in maintaining normoglycemia in the brain dead organ donors, without severe hypoglycemia. Furthermore, the anti-inflammatory effect was clearly demonstrated in the experimental group as expressed by the decreased levels of several pro-inflammatory cytokines as compared to the control group following treatment. Future studies with a focus on the effect of such therapy on the transplanted organs and patients are warranted. / L'état de mort cérébrale est considéré comme un stress majeur pour l'organisme qui est associé à une réaction inflammatoire massive, que l'on appelle la « tempête de cytokine », caractérisée par la libération excessive de cytokines pro inflammatoires. Cette réaction inflammatoire aiguë chez les donneurs d'organe en état de mort cérébrale est à l'origine de perturbations majeures de l'homéostasie du glucose qui provoquent l'insulinorésistance et l'hyperglycémie systémique. L'hyperglycémie aiguë est étroitement liée à la réaction inflammatoire et se traduit par un risque accru de morbidité et de mortalité. Une inflammation sévère chez les donneurs en état de mort cérébrale peut également augmenter l'immunogénicité du greffon avant la transplantation et le risque de dysfonctionnement de ce dernier à l'issue de la transplantation. Outre qu'elle permet de maintenir la normoglycémie, l'insulinothérapie a des effets anti inflammatoires selon des études cliniques ou expérimentales. L'objectif du présent projet était d'étudier les propriétés anti-inflammatoires de l'insuline administrée à fortes doses à des donneurs en état de mort cérébrale et d'établir si cette thérapie permet de maintenir la normoglycémie chez ces donneurs. L'effet anti-inflammatoire a été mesuré en comparant les fluctuations des niveaux de cytokines sériques chez ces donneurs. L'insulinothérapie a été administrée à l'aide de la pince hyperinsulinémique normoglycémique (PHN). L'étude a été effectuée dans le contexte d'un essai pilote prospectif inscrit sur le site clinicaltrial.gov (NCT01304290). Quinze donneurs en état de mort cérébrale y ont pris part, dont six ont fait partie du « groupe expérimental » qui a suivi le protocole PHN et neuf du « groupe de contrôle ». L'administration d'insuline a duré au moins six heures et s'est poursuivie jusqu'au moment du prélèvement d'organe. La répartition des donneurs dans le groupe expérimental ou le groupe de contrôle était fondée sur le lieu de la procédure de don. Des échantillons de sang ont été prélevés chez tous les patients à différents moments. Ces échantillons ont été analysés afin de mesurer les niveaux de plusieurs cytokines inflammatoires prédéterminées. Des comparaisons ont été établies entre les fluctuations de ces niveaux et l'administration de la thérapie chez les patients des deux groupes. L'insulinothérapie à forte dose à l'aide de la PHN a permis de maintenir la normoglycémie chez les donneurs d'organe en état de mort cérébrale sans provoquer d'hypoglycémie sévère. Qui plus est, à l'issue du traitement, l'effet anti inflammatoire a été clairement démontré dans le groupe expérimental, comme en témoignent les niveaux réduits de plusieurs cytokines pro inflammatoires, comparativement au groupe de contrôle. Des études ultérieures s'imposent qui porteraient essentiellement sur l'effet de cette thérapie sur les organes transplantés et les patients.

Recently, there has been a growing movement toward an Electronic Health Record (EHR) to improve quality of care. The paper-based medical record is still the primary source of information in today’s medical practice. In order to design the EHR, knowledge with regard to the current medium of documentation is required. In the MUHC Cedars Breast Clinic, 112 medical records for 7 surgeons were audited to determine what was recorded in the initial visits between year 2002 and 2003. A Likert scale questionnaire was developed and included 46 questions derived from the chart review. It was introduced to assess their opinions on important variables in managing breast patients. The correlation between the medical records and surgeons’ opinions was then sought. The majority of data points had a low rate of documentation with wide variation; breast cancer risk factors were recorded in less than one third of charts. Family history and physical examinations had relatively high rates of documentation. The survey showed a considerable variation among surgeons’ opinions. Surgeons reported that they addressed 63% of all data points (29 of 46 questions) very often/always. There was weak correlation between what each surgeon records and what he/she thinks is important. / Récemment, il y a eu un mouvement grandissant vers le dossier électronique de santé (EHR) pour améliorer la qualité du soin. Le dossier médical sur papier est toujours la source primaire d'information dans la pratique en matière, aujourd'hui. Afin de concevoir EHR, la connaissance en ce qui concerne le milieu courant de la documentation est exigée. Dans la Clinique du sein de l'Institut des cèdres du CUSM, 112 disques médicaux pour 7 chirurgiens ont été apurés pour déterminer ce qui est enregistré dans les visites initiales en l'année 2002 et l'année 2003. Un questionnaire de balance de Likert comprenant 46 questions dérivées des dossiers a été présenté pour évaluer leur avis sur des variables importantes dans les patients de gestion de sein. La corrélation entre ces deux a été cherchée. La majorité de points de repères a eu un bas taux de documentation avec une grande variation; des facteurs de risque de cancer de sein ont été enregistrés dans moins d'un tiers de dossiers. Les antécédents familiaux et les examens physiques ont eu des taux relativement élevés de documentation. L'aperçu a montré une variation considérable parmi l'opinion des chirurgiens. Les chirurgiens ont rapporté qu'ils ont adressé 63% de points de repères (29 de 46 questions) très souvent/toujours. Il y avait corrélation faible entre ce que chaque chirurgien enregistre et quel il/elle pense est important. fr

The purpose of this study was to examine the radiographic and histologic response. to corundum blasted implant surfaces of varying roughness in a canine total hip arthroplasty model. Three types of tapered femoral implants were made from titanium alloy and were identical in every respect except surface finish. The entire surface of the femoral implant possessed either a 2.9, 4.2 or 6.7 micrometer average surface roughness (Ra) from blasting with 60, 24, or 16 grit corundum particles, respectively. Staged bilateral total hip arthroplasties were performed such that each dog received a 60 grit on one side and a 24 grit or 16 grit implant on the contralateral side. Twenty-two stems in 11 dogs were evaluated at 6 months. The appearance of the bone implant interface was qualitatively characterized. Bone apposition and average bone-implant contact length were determined. Twenty-one of the stems demonstrated osseointegration while one stem developed a stable fibrous interface. All three types of corundum blasted implants demonstrated consistently high amounts of bone apposition, averaging 30.5%. Abundant new peri-implant bone consistently formed, particularly within the intramedullary canal where trabeculae spanned implant-cortical gaps up to 5 mm and established osseointegration ration. There was no statistical difference amongst bone apposition with the 60, 24, and 16 grit stems which averaged 31.7%, 32.0% and 27.9% respectively. However, the pattern of new bone formation was different in that the average length of each region of bone apposition for the 60 and 24 grit surfaces was 50% greater than that for the coarser 16 grit surface (p < 0.02). Through detailed qualitative and quantitative radiographic and histologic elucidation of the osseous response to corundum blasted hip implant surfaces, this study provided new understanding of their potential for biologic fixation. Corundum blasted surfaces represent an important and valuable technology for the design of non

Histone acetylation plays an important role in regulating chromatin structure and thus gene expression. Analysis of histone deacetylase (HDAC) activity in S. cerevisiae revealed the presence of two deacetylase complexes, one containing Hda1 as its catalytic subunit, and the other possessing Rpd3. The three previously identified human HDAC proteins, HDAC1-3, were found to be homologs of Rpd3. This observation suggested that mammalian cells might contain an uncharacterized class of biochemically distinct Hda1-like proteins. The goal of my project has been to identify and characterize mammalian HDAC proteins which are similar to Hda1. I first identified the human histone deacetylase HDAC4, which contains a carboxy-terminal region significantly similar to the catalytic domain of yeast Hda1. When tethered to a promoter, HDAC4 functions as a transcription corepressor. Furthermore, HDAC4 interacts with the transcription factors MEF2 and RFXAf\lK and represses transcription of their target genes, supporting the notion that HDAC4 is a transcription corepressor in vivo. Surprisingly, HDAC4 is localized mainly in the cytoplasmic region and shuttles between the nucleus and the cytoplasm. Nucleocytoplasmic shuttling of HDAC4 is controlled by multiple mechanisms. HDAC4 possesses a nuclear localization signal (NLS) and a nuclear export signal (NES) for its dynamic nucleocytoplasmic trafficking. Binding of 14-3-3 proteins exposes the NES of HDAC4, which then results in its nuclear export. From this work, I have identified HDAC4 and shown that it functions as a transcription corepressor whose activity is regulated by nucleocytoplasmic shuttling.

The terminal events leading to periprosthetic osteolysis are multifactorial and attempts to modulate this process after the stage of modulator release have been futile. Cell death at the osteolytic interface of failed total hip arthroplasties (THAs) may occur via one of two modes---Apoptosis (programmed cell death/cellular suicide) vs. Necrosis. Apoptosis (PCD) is an active form of cell death that results in---among other things---orderly fragmentation of DNA and specific protein synthesis. The purpose of this study was to determine the mode of cell death at this interface. TdT-mediated dUTP nick end-labeling (TUNEL) stain and immunodetection of terminin protein were used to identify apoptosis. / Our studies demonstrated that 31% (range 7--56%) of cells of pseudomembrane were positive for TUNEL stain. Moreover, the presence of apoptosis was the same at both the femoral and acetabular sides of the prostheses. In addition, pseudomembrane (PM) specimens stained for the 30 kDa terminin protein, an apoptosis-specific protein. The results demonstrate that apoptosis is occurring at the PM-bone interface of THAs suggesting that apoptosis, related events may be associated with periprosthetic osteolysis.

A prospective, randomized, experimental study was performed to assess the treatment of mandibular continuity defects by distraction osteogenesis, using the rabbit model. This method of treatment was compared to a control group, which had treatment by traditional means, using a fixation plate. Eight animals were randomized into one of the two groups. / The treatment methods were assessed by clinical, radiographic, and histologic examinations. / Clinically, the experimental specimens had greater dimensions of bone formation in the defects than their matched controls. / Radiographically, there was a higher percentage of radiopacity in the defects of the experimental group compared to the controls, although not statistically significant. / Histologically, there was a statistically significant higher percentage of bone fill in the defects of the experimental group compared to the controls. Three of the four experimental specimens (75%) developed bony union at the 'docking site'. / A cost-efficient animal model was developed for the study of bifocal distraction in the treatment of mandibular continuity defects. The critical-sized mandibular defect in the rabbit model was found to be a minimum of 4mm.

In the context of the choice of treatment for end-stage renal disease, three approaches to utility assessment were examined to determine which captures prospective patients' values best. The standard gamble (SG), time tradeoff (TTO) and visual analogue scale (VAS) were compared for their test-retest reliability and convergent validity. The study population consisted of patients who attended nephrology clinics at one of three teaching hospitals in the city of Montreal. Sixty-six patients were interviewed three times by one of two interviewers. They were taught about the treatments using an information package developed expressly for the study and a video produced by a pharmaceutical company for use in this decision context. Utilities for treatment were measured on two occasions about one week apart. / Patients differed widely in the utilities provided (responses ranged from 0 to 100) but mean utilities were similar across the treatments assessed. Because of the wide variation among subjects, the intraclass correlation coefficients for test-retest reliability were high to moderate: 0.87 for SG, 0.73 for TTO and 0.64 for VAS. However, the precision of the methods, as measured by the standard deviation of the measure from one occasion to the next within subjects, was low with SD's of 10 for SG, 14 for TTO and 13 for VAS assessments. The use of correlation coefficients as a measure of reliability and convergence in this context was challenged. / SG and TTO utilities and SG and VAS utilities (when anchoring effects were controlled) were unbiased estimates of one another, but the degree of agreement between each pair was low. The VAS assessments produced higher values than the TTO assessments. Both SG and VAS were susceptible to strong anchoring effects; in other words, the utilities obtained were different when the best and worst outcomes used to anchor the ends of the scale were changed from full health and death to full health and the worst treatment. / Subject characteristics and study factors were investigated for associations with reliability and with convergence and with the absolute level of utility. The standard gamble approach was strongly associated with many of the factors, while the time trade-off and the visual analogue utilities were associated with fewer. / The poor reliability of the methods raises questions about their use in decision aids for individuals. The lack of agreement among the methods indicates that the methods cannot be used interchangeably.

Certain regions adopt an aggressive approach (routine cardiac catheterization and frequent invasive revascularization) to care for acute myocardial infarction (AMI), while other regions adopt a conservative approach (selective use of invasive procedures). Administrative data provide a means to estimate the effects of these variations on patient outcomes, but they are limited by their potential for confounding bias due to unobserved case-mix variation as treatment assignment is not random. This study applied instrumental variables, a methodology that can account for this bias, to estimate the effectiveness of aggressive care in a Canadian patient population. The study used administrative data of hospital admissions and health services for all patients admitted for a first AMI in Quebec in 1988 (n = 8674). Incremental (marginal) mortality up to 4 years after admission was measured using distances to hospitals offering aggressive care as instrumental variables. / Patients living closer to hospitals offering aggressive care were more likely to receive aggressive care than patients living further away (e.g. 26% versus 19%, respectively, received catheterization within 90 days). However, instrumental variable estimation found that aggressive care was not associated with marginal mortality benefits in comparison to conservative care (e.g. adjusted difference at 1 year: 4%; 95% CI: -11% to 20%). / The aggressive approach to post-AMI care is not associated with marginal mortality benefits in Quebec.